Some libraries use patron attributes to track statistics that are always the same for some of their patron categories, but other categories need the ability to select from a list of attributes. I don't know how difficult this would be, but one option might be for under patron attribute settings, have a dynamic display that would list all patron attributes that are available for patrons of this category. For each it would have either a free text field (for uncontrolled attributes) or a dropdown (if controlled by an authorised value) that would allow entering a default for this patron category only. Likely would depend on either bug 22730 or 20682, though I'd need a developer to confirm that.